1. Field of the Invention
The present invention relates to a fuse unit used for power distribution in a vehicle equipped with two batteries.
2. Description of the Related Art
A fuse unit is directly attached to an onboard battery so as to distribute and supply electricity to loads such as electrical components (e.g., Japanese Unexamined Patent Application Publication No. 2011-86510). Such a fuse unit protects onboard electrical components against overcurrent by blocking current flow paths. When two batteries are mounted on a vehicle, a fuse unit is directly attached to one of the batteries.
FIG. 1 is a view showing a conventional fuse unit 100 used in a vehicle on which two batteries are mounted. FIG. 2 is a circuit diagram of a circuit body placed in the fuse unit 100.
The fuse unit 100 charges a first battery and a second battery (not shown in the figure) mounted on a vehicle with electricity generated by an alternator (not shown in the figure) through driving of the vehicle. The fuse unit 100 supplies currents from the first battery, the second battery and the alternator to electrical components (loads).
The fuse unit 100 includes a unit main body 110 (FIG. 1) and a circuit body 200 (FIG. 2) buried in the unit main body 110. The fuse unit 100 will be described below with reference to FIG. 1 and FIG. 2.
The unit main body 110 is entirely made of an insulating resin. As shown in FIG. 1, the unit main body 110 includes an upper surface portion 120 and a side surface portion 130 and is formed into an L-shape bent substantially at a right angle in a manner such that one end of the upper surface portion 120 is continuously connected to the side surface portion 130. The upper surface portion 120 of the unit main body 110 is placed and fixed onto the upper surface of the first battery so that the side surface portion 130 is positioned along the side surface of the first battery. Thus, the fuse unit 100 is attached to the first battery in a hanging state.
The upper surface portion 120 of the unit main body 110 includes a first battery connecting portion 121, an alternator connecting portion 122 and a second battery connecting portion 123. A first battery connecting end 201 of the circuit body 200 is located at the first battery connecting portion 121. An alternator connecting end 202 of the circuit body 200 is located at the alternator connecting portion 122. A second battery connecting end 203 of the circuit body 200 is located at the second battery connecting portion 123.
An insertion hole 205 is formed in the first battery connecting end 201. A connecting bolt (not shown in the figure) of a battery terminal connected to a battery post projecting from the upper surface of the first battery, is inserted into the insertion hole 205. The first battery connecting end 210 is connected to the first battery via the connecting bolt inserted into the insertion hole 205.
The alternator connecting end 202 is provided with an alternator connecting bolt 206. The alternator connecting bolt 206 vertically extends from the alternator connecting end 202. The alternator connecting bolt 206 extends in the same direction as the connecting bolt of the battery terminal connected to the first battery. The alternator connecting bolt 206 is connected to the onboard alternator via a wire. Thus, the alternator connecting end 202 is connected to the alternator.
The second battery connecting end 203 is provided with a second battery connecting bolt 207 vertically extending therefrom. The second battery connecting bolt 207 vertically extends from the second battery connecting end 203. The second battery connecting bolt 207 extends in the same direction as the alternator connecting bolt 206. The second battery connecting bolt 207 is connected to the second battery via a wire. Thus, the second battery connecting end 203 is connected to the second battery. The second battery connecting bolt 207 has the same diameter and extends in the same direction as the alternator connecting bolt 206.
As shown in FIG. 2, the first battery connecting end 201 is connected to the alternator connecting end 202 via a first fusible portion 211. The alternator connecting end 202 is connected to the second battery connecting end 203 via a second fusible portion 212. The first fusible portion 211 and the second fusible portion 212 are located at the upper surface portion 120 of the unit main body 110 (refer to FIG. 1). The first fusible portion 211 and the second fusible portion 212 each serve as a fuse that blows out once an overcurrent flows therethrough so as to protect the first battery and the second battery against the overcurrent from the alternator.
Since the first battery connecting end 201, the alternator connecting end 202 and the second battery connecting end 203 are all located at the upper surface portion 120 of the unit main body 110, the fuse unit 100 can be connected with the first battery, the alternator and the second battery simply via the upper surface portion 120 of the unit main body 110.
The side surface portion 130 of the unit main body 110 is provided with a load connecting portion 131 to be connected with a plurality of onboard loads 8 (refer to FIG. 2). The connection of the fuse unit 100 with the plural loads 8 is implemented at the side surface portion 130 of the unit main body 110. The alternator connecting end 202 is provided with a plurality of load-side terminal portions 215. The load-side terminal portions 215 are respectively connected to the onboard loads 8 via third fusible portions 213. Accordingly, the electricity generated by the alternator through driving of the vehicle is distributed and supplied to the onboard loads 8. As shown in FIG. 1, the third fusible portions 213 are located at the side surface portion 130 of the unit main body 110.
The connection of the fuse unit 100 with the first battery, the second battery and the alternator is carried out in the process of assembling the vehicle. The alternator connecting bolt 206 is connected to the alternator via the terminal of the wire while the fuse unit 100 is placed on the first battery. The second battery connecting bolt 207 is connected to the second battery via the terminal of the wire. Here, since the alternator connecting bolt 206 and the second battery connecting bolt 207 extend in the same direction and have the same diameter, the respective terminals of the wires may incorrectly be connected to the wrong bolts. Such incorrect assembly should be avoided because it inhibits the fuse unit 100 from operating properly.